It is well known among prosthesis wearers that downhill walking is problematic. If the prosthesis wearer does not have the possibility of adjusting the angle of the foot, the walk downhill gets such that only the heel has contact with the ground. Above a certain degree of foot angle it is difficult to bear up the body weight so that the knee does not collapse because of the lack of essential groups of muscles. Therefore, prosthesis wearers often choose to walk sidewards when walking downhills.
Further, prosthesis wearers utilizing a foot prosthesis which is not vertically adjustable have problems changing to another shoe with a different heel height, and have difficulty walking without shoes. Individual, vertical adjustment of the foot is desirable because such adjustability can reduce problems with pain in the user's back and can minimize wear on the user's hips.
Through for instance U.S. Pat. No. 2,749,557 is known an adjustable foot, however it is only adjustable to three different angular positions.
Furthermore, SE-B-456 134 shows a prosthesis foot where the angular positions of the foot are adjusted with a screw existing in the heel of the foot. The prosthesis wearer must turn the screw a number of turns to change the angle position, which requires a certain work effort. The principle of changing the angle shown in this document has the great disadvantage that the length of the leg changes, which results in that the prosthesis wearer can have one leg shorter or longer than the other in certain situations.
Further, SE-B-469 780 shows an additional example of a prosthesis foot where the angle position of the foot can be adjusted, in this case using a ball screw and ball nut.
Furthermore, WO 96/25898 shows a device of the kind mentioned in the preamble.
The invention relates to a device of the kind mentioned in the preamble, which can easily be adjusted to the weight and walk pattern of the prosthesis wearer and which is reliable and simple and cheap to manufacture.